Does anyone have a picture of this cross?
I put a blue Orpington rooster over a cornishX hen and got this blue barred cockerel. You might get something like him. But I believe my cornishX was recessive white, as I got all colored chicks out of that mix. Others who have crossed cornishXs seem to get mostly white chicks.
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I know someone many years ago used some of the Ross 500 blood in his standard Barred Rocks, to get the size up. I think you'll get a mix of barred and white and maybe other colors if the hen was recessive, and within a few generations should be back to all barred again, if done well.